Is artificial intelligence really just human intelligence?
This is an old question, going back at least to 1950. It is one of the original objections to AI that Turing considers and attempts to refute in his seminal 1950 paper Computing Machinery and Intelligence.

Turing actually attributes this objection to Lady Lovelace, apparently quoted by another author. In Turing's paper, this is objection #6: Lady Lovelace's Objection, in section 6 of the paper. The objection is concisely stated as


  The Analytical Engine has no pretensions to originate anything. It can
  do whatever we know how to order it to perform.


where "The Analytical Engine" was an early design for an all-mechanical general purpose computer.

Turing offers two replies to this objection. First, he reminds us that computer programs have bugs. That is, they often do things their creators did not intend. This is unsatisfying to many readers, but it does address the objection: programs may act in ways that are unrelated to our intelligence, and in doing so, might display unexpected intelligent behaviors. In this sense, their intelligence would not be an intentional product of human intelligence.

Turing's stronger objection comes from an anticipation that learning would eventually move to the center of AI research (keep in mind again, this is written in 1950, well before any reasonable learning algorithms had been proposed!). Turing uses the example of a robotic child in Section 7 of the paper (Learning Machines) to elaborate on his point. A child is created by its parents, but, endowed with the ability to learn, quickly begins to display behaviors its parents do not anticipate or intend. No one would suggest that a person's intelligence is "really just" the intelligence of their parents, even though their parents created them, and are partially responsible for that intelligence.

Likewise, Turing's proposed robotic child is created by a parent, but, endowed with learning, quickly begins to engage in behaviors the parent does not anticipate or intend. Therefore, machine intelligence need not be reduced to just human intelligence.

I think that if Turing were alive today, he would agree that we are now beginning to move into the era of learning machines he anticipated. Some of our programs now engage in intelligent behaviors that we do not anticipate or understand. For example, self-driving cars now kill or maim people, because they have learned behaviors their creators did not intend or anticipate, perhaps not unlike a reckless teenage driver.